This invention relates to improved connection assemblies and in particular but not exclusively to an improved method and means for interconnecting flexible tubes or connecting flexible tubes, such as flexible tubes of a solar heat exchanger, to a header pipe.
At present there are many solar water heating arrangements available which operate to provide hot water for domestic purposes or at a lower temperature for say swimming pool heating or space heating. One such proposal for swimming pool heating, for example that which is described in U.S. Pat. No. 4,269,172, provides a multi-tube plastics absorber which is mounted on the roof of a building so that water flowing through the tubes receives heat directly from the sun and by conduction from the roof's surface. In the above arrangement the absorber tubes communicate at one end with respective inlet and outlet headers via plug-in adapters, whilst the respective tubes of the absorber at the opposite end are interconnected by push-in transfer means so that water flowing in the inlet header passes through the absorber and back to the outlet header.
In each instance plastic solvent glue or the like is normally used to seal the respective connections to prevent leakage. It has been found, however, that the solvent glue tends to lose its effectiveness over a period of time and thus the seal is often broken. If glue is not used, the wall of the tube must be made relatively thick so that the tube itself acts as a clamp on the plug-in adapter or transfer means.
In other arrangements, a multitube absorber is looped back on itself and the opposite ends of the tubes are plugged into the header pipes by means of cylindrical plugs which are inserted into the ends of the tubes and which are then forced into the apertures in the header pipes to provide the sealing effect. In this instance, the wall of the tube acts as the sealing medium and again must be relatively thick to ensure reliability in use. However, use of relatively thick walled tube for the connection assemblies is wasteful and expensive and not required for the heat receiving section of the absorber. A further disadvantage of the loop arrangement is that thicker material is also required at the looped ends to prevent the channels from crimping and closing off. Use of a thick walled tube in these instances causes the appearance of the absorber in situ to be unacceptable as the loop tends to stand up rather than lay flat on the roof. Furthermore, at the loop ends the heat contact between the roof and the absorber is broken resulting in loss of conducted heat energy from the roof.
A further disadvantage of the known swimming pool heat exchanger assemblies is that the inlet and outlet headers are either provided with a plurality of pre-formed apertures therealong or the pipes require manual drilling to enable the plug-in connections to be made. If the apertures are pre-formed, those apertures not in use must be plugged up in some manner which can cause leakage problems over a period of time, whilst if non-apertured pipes are used, a relatively high skill is required to ensure accurate drilling of the apertures on site.